High levels of black carbon pollution in the north-eastern Indian city of Guwahati is responsible for accelerating glacier melt in the Himalayas, according to new research by scientists.

Guwahati, the capital city of Assam state near the eastern Himalayas, is situated on the bank of the Brahmaputra River. The Brahmaputra River Valley has been experiencing extreme regional climate change in the recent years and the carbon emissions from Guwahati, the largest city in the valley, are believed to play a major role warming the climate.

A research team from Desert Research Institute in Nevada, United States, with support from NASA, calculated that on average the high level of pollutants have resulted in an increased daily temperature of 2 degrees Celsius. The research reveals the affect of black carbon aerosols (emitted from vehicles and other combustion sources) on the atmosphere of the region. Strong radiative heating due to wintertime black carbon aerosols in the Brahmaputra River Valley not only affects the climate, these pollutants are carcinogenic and present a serious health hazard. These pollutants are being pushed out to the Himalayas, melting glaciers and permafrost, and interfering with the monsoon cycle, causing abrupt rainfall and droughts.

According to their research paper published last month in Geophysical Research Letters, Guwahati has one of the highest black carbon pollution levels in the world. The concentration of black carbon pollution during winter observed in the city was higher than levels in the other large cities in India and China, and much higher than in urban locations in Europe and the US. Rajan K. Chakrabarty, a researcher on the project who comes from Guwahati, said that rapid urbanisation and poor environment quality control in Guwahati was giving rise to such high levels of black carbon.

Rajan Chakravarty, Scientist.

The report reveals that more than 400,000 vehicles ply Guwahati’s roads every day. About 70% of these vehicles don’t have emission clearance certificates, and emit excessive amounts of black carbon and other very toxic pollutants into the atmosphere. Another factor contributing to the city’s pollution is the unplanned and open burning of solid waste disposal in the city.

According to Chakravarty: “The wind blows pollution fromAssam into the Tibetan region andChina. In the Tibetan region, black carbon pollutants get deposited on the glaciers and reside in the atmosphere. Black carbon particles absorb incoming sunlight and trap heat in the atmosphere. They act like an invisible blanket in the atmosphere and warms up the atmosphere.”

Chandan Kumar Duarah, an environmentalist and independent researcher said: "This alarming issue has already been reported a section of print media in the region and the Assam Government as well as the Union Ministry of Environment andForestare yet to recognise this alarming rise in black carbon pollutants. Strong measures are needed to control vehicle pollution immediately and the state machinery must quickly act upon it.”